1. Field of the Invention
The present invention relates to a braking structure of a measuring tape, especially to a braking mechanics by which the measuring tape can be pulled out successfully, and the measuring tape wheel is prevented to rotate idly and the measuring tape is prevented to be wound by error.
2. Description of the Prior Art
The prior art measuring tape is shown in FIG. 1. The measuring tape has a front housing 10, a rear housing 11, a shaking rod 12 and a measuring tape wheel 13. The shaking rod 12 and measuring tape wheel 13 are formed integrally. The measuring tape wheel 13 can be rotated between the front housing 10 and the rear housing 11. A convex shaft 14 is formed on the side thereof and is inserted into the rear housing 11 so to rotate therewithin. A measuring tape 15 is wound around the measuring tape wheel 13. When the measuring tape 15 is pulled, the measuring tape wheel 13 is also rotated.
However, this prior art measuring tape has the following disadvantages:
(1) When the measuring tape 15 is pulled, the measuring tape will drive the measuring tape wheel to freely rotate between the front housing 10 and the rear housing 11. During measurement, the force applies on the measuring tape can not be well controlled by operator. In order to rapidly operate, the measuring tape 15 is often pulled rapidly so that the measuring tape wheel 13 with the housing will idly rotate, therefore, the measuring tape 15 is detached from the measuring tape wheel 13 so that the operator must waste much times for rewinding the measuring tape 15. PA1 (2) If the force applied on the measuring tape 15 is too large, and the idle rotation of the measuring tape wheel is too long so that the released measuring tape is too long and is intricate together. This will affect the work and operator need waste much time to process this condition. PA1 (3) The prior art measuring tape has some inconvenience as it is used in a long measuring tape, since the design of a prior art measuring tape is suitable in short and small diameter measuring tape made by metal. Wherein in the prior art measuring tape, as the measuring tape is pulled out, the spring compresses and a push button is pressed so that a pressing piece will press the surface of a steel rule, thus it is fixed. As the measuring tape is wound, the control button is pushed backwards, the pressing piece will release from the metal measuring tape. By the rewind force of the spring, the measuring tape is rewound. But, this prior art measuring tape can not be used in a long, nonmetal engineering measuring tape.